In many countries nodding is a communicative signal meaning approval and head shaking denial.

Prof Kawahara said: "The results showed the nodding head motion significantly increased ratings of subjective likability and approachability relative to those of the shaking or control conditions, whereas the shaking motion did not influence the ratings.

"Furthermore it was shown a nodding head motion of the computer-generated models primarily increased likeability attributable to personality traits rather than to physical appearance.